1. Field of the Invention
The present invention relates to methods and apparatus for therapeutically treating injuries using ultrasound. More particularly, the present invention relates to methods and apparatus which utilize an ergonomically constructed ultrasonic transducer assembly configured to cooperate with a placement module for placement in proximity to a cartilage and/or osteochondral injury and/or defect to stimulate cartilage growth.
2. Description of the Related Art
The use of ultrasound to therapeutically treat and evaluate bone injuries is known. Impinging ultrasonic pulses having appropriate parameters, e.g., frequency, pulse repetition, and amplitude, for suitable periods of time and at a proper external location adjacent to a bone injury has been determined to accelerate the natural healing of, for example, bone breaks and fractures.
U.S. Pat. No. 4,530,360 to Duarte describes a basic non-invasive therapeutic technique and apparatus for applying ultrasonic pulses from an operative surface placed on the skin at a location adjacent a bone injury. To apply the ultrasound pulses during treatment an operator must manually hold the applicator in place until the treatment is complete.
The Duarte patent as well as U.S. Pat. No. 5,520,612 to Winder et al. describe ranges of RF signal for creating the ultrasound, ultrasound power density levels, ranges of duration for each ultrasonic pulse, and ranges of ultrasonic pulse frequencies.
U.S. Pat. No. 5,003,965 to Talish et al. relates to an ultrasonic body treatment system having a body-applicator unit connected to a remote control unit by sheathed fiber optic lines. The signal controlling the duration of ultrasonic pulses and the pulse repetition frequency are generated apart from the body-applicator unit. Talish et al. also describes a mounting fixture for attaching the body-applicator unit to a patient so that the operative surface is adjacent the skin location.
While the systems described in these patents relate to therapeutic methods and apparatus for ultrasonic treatment of hard and soft tissue injuries and defects, there is a need for ergonomically configured signal generators and transducers for the treatment of cartilage and/or osteochondral injuries and/or defects. Further, a need exists for an apparatus which optimizes the treatment of cartilage and/or osteochondral injuries and/or defects.
A cartilage and/or osteochondral injury and/or defect typically involves damage to the cartilage which lines articulating bones (articular cartilage), such as the bones of the knee, elbow, shoulder and ankle. Osteochondral injuries can be treated by chondral and/or osteochondral drilling causing blood flow at the site. The aim of chondral drilling is to stimulate cartilage regeneration as part of the healing process. However, the resulting nonhyaline or fibrocartilage produced is biomechanically inferior to articular cartilage, does not have comparable proteoglycan content, and may consist primarily of a thin unorganized layer of collagen. Further, it has been observed that degeneration of the new tissue generally occurs over time, requiring the need for additional reconstructive surgical treatment.
Other methods of treatment include: the transplantation of non-weight bearing cartilage to the injury and/or defect site; inducing a fracture at the injury and/or defect site; placing a carbon fiber matrix to induce cartilage formation; and autologous chondrocyte implantation (ACI). ACI entails removing chondrocytes capable of regenerating hyaline-like cartilage from the body and culturing them for several weeks. During the culture process, the number of cells increases approximately 0.15 times that of the original tissue sample. The cultured cells are then transplanted through an arthrotomy. A small piece of periosteum, the skin covering a bone, is taken from the patient's tibia. The periosteum is then sutured over the defect to provide a protective cover for the cultured cells. The cultured cells are injected under the periosteum into the defect where they will continue to multiply and produce a durable repair tissue. However, ACI increases the healing time since the chondrocytes need to be cultured before they are transplanted to the patient.
Therefore, there is a further need for a method and apparatus to stimulate cartilage regeneration which produces fibrocartilage which is biomechanically equal or superior to articular cartilage, has comparable proteoglycan content, and consists of a thick organized layer of collagen. Further still, a need also exists for an apparatus which stimulates cartilage regeneration and where the regenerated cartilage does not degenerate over time requiring additional treatment or reconstructive surgery. Further, there is a need for an apparatus which stimulates cartilage regeneration and significantly reduces the healing time.